What would cause my knee to hurt and cause pain up and down my leg? I injured it this summer. A tight muscle in the hip was the cause then.

Hip. Probably bursitis, most common hip problem, but if there is sensory change or pins and needles feelings could be minor nerve injury from injury to a skinnerve in the side of the leg(meralgia paresthetica) or a true disc related nerve pain. Pressure on the injured thigh area will reproduce meralgia but not a disc problem and both should improve with rest, though a disc problem could be serious.